Heart valve prosthesis and method

ABSTRACT

A heart valve prosthesis (100) comprises a housing component (110) and a valve component (130). The housing component (110) comprises a housing body (111) having a housing passage (112) extending therethrough. The housing body (111) is configured to be located in, or adjacent to and communicating with, a native valve orifice (16) of a heart (10) and to engage structure of the heart (10) to fix the housing body (111) in relation to the valve orifice (161). The housing component (111) is collapsible for delivery via catheter (2). The valve component (130) comprises a valve body (131) having a valve passage (132) extending therethrough. The valve body (131) is configured to be fixed within the housing passage (112) with the valve passage (132) extending along the housing passage (112). One or more flexible valve elements (131) is/are secured to the valve body and extend across the valve passage (132) for blocking blood flow in a first direction through the valve passage (132) whilst allowing blood flow in the opposing direction. The valve component (130) is collapsible for delivery via catheter (2) separate to the housing component (110). An associated method of replacing a failed or failing heart valve utilising the heart valve prosthesis (100) is also disclosed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a national stage filing of PCT Patent ApplicationSerial No. PCT/AU2009/001513, filed Nov. 20, 2009, which claims thebenefit of priority to Australian Provisional Patent Application No.2008906045, filed Nov. 21, 2008, and Australian Provisional PatentApplication No. 2009900460, filed Feb. 9, 2009, all of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a heart valve prosthesis and associatedmethod of treating a failed or failing heart valve. The invention isparticularly related to a two-component heart valve prosthesis that isimplantable by a two-step approach.

BACKGROUND OF THE INVENTION

Heart valve regurgitation is a condition whereby the heart valve doesnot seal completely as a result of disease or injury, and may have fatalconsequences. Valve stenosis is a condition where the valve is narrowedand cannot open normally. Whilst valve stenosis can be treated byvalvuloplasty (by balloon dilatation), this often results in the valveleaking and may require valve replacement. Aortic valvuloplasty isgenerally not a very effective or durable treatment for aortic stenosis.

Malfunctioning heart valves have typically been replaced with mechanicalor biologic heart valve prostheses using highly invasive open-heartsurgical techniques. Surgical mitral valve replacement is quite invasiveand cannot be performed on many sick patients with severe mitralregurgitation. This procedure often results in resection of the anteriorleaflet of the mitral valve which could lead to further left ventriculardysfunction. Whilst there has been some success in developingreplacement stent based aortic valve prostheses for delivery viapercutaneous catheter-based methods, these techniques have not beenparticularly successful when applied to mitral valve prostheses.

Mitral valve replacement is firstly made difficult as a result of theanatomy of the mitral valve, and particularly that of the mitral valveannulus in which the mitral valve leaflets are located. The mitral valveannulus is typically very distorted, and of unpredictable andnon-uniform geometries, as compared to the relatively uniform aorticvalve annulus. This unpredictable anatomy makes it difficult to design apre-constructed mitral valve prosthesis that would fit the mitral valveannulus in a satisfactory manner for safe, stable and meticulousdeployment.

Further, unlike the aortic valve annulus which is entirely surrounded bymuscular tissue, the mitral valve annulus is bounded by muscular tissueon the outer wall only, with the inner side of the mitral valve annulusbeing bounded by a thin vessel wall which separates the mitral valveannulus and the aortic outflow tract. As a result, the mitral valveannulus cannot be subjected to any significant radial forces, as wouldbe typical with an expanding stent type of valve prosthesis, as suchradial forces would tend to collapse the aortic outflow tract, resultingin circulatory collapse with likely fatal consequences. As such, stenttype valve prostheses are presently generally not suitable for use as areplacement mitral valve.

Mitral valve replacement techniques have also generally advocatedremoval of the native valve prior to location of the replacement mitralvalve prosthesis. This is a technically extremely challenging taskassociated with the potentially fatal complication of profound mitralregurgitation that may not be adequately addressed by the subsequentvalve replacement. The lack of an effective mitral valve may lead tooverwhelming hemodynamic instability that may not be tolerated by thealready compromised left ventricle and overwhelming pulmonary oedema mayrapidly result.

Known stent based aortic valves are also not generally repositionableand therefore precise placement is difficult. This could result inimportant structures such as the coronary arteries being compromised asa result. Moreover, post-stenotic dilatation of the aorta may result inimprecise apposition of current stent based aortic valves, resulting insignificant paravalvular leaks. For the same reason, current stent basedaortic valves are typically not recommended for the treatment of pureaortic regurgitation. Current stent based aortic valves are alsotypically subject to fatigue and resultant fracture.

Further, various previously proposed replacement heart valve prosthesesare relatively bulky and are thus not suited for percutaneous deliveryusing small diameter catheters, with more invasive larger cathetersbeing required.

OBJECT OF THE INVENTION

It is the object of the present invention to substantially overcome orat least ameliorate at least one of the above disadvantages.

SUMMARY OF THE INVENTION

In a first aspect, the present invention provides a heart valveprosthesis comprising a housing component and a valve component;

wherein said housing component comprises a housing body having a housingpassage extending therethrough;

said housing body being configured to be located in, or adjacent to andcommunicating with, a native valve orifice of a heart;

said housing component being configurable between a housing collapsedstate for delivery to the native valve orifice via catheter and ahousing expanded state to engage structure of the heart to fix saidhousing body in relation to the native valve orifice;

further wherein said valve component comprises:

a valve body having a valve passage extending therethrough;

said valve body being configured to be located at least partially withinsaid housing passage with said valve passage extending along saidhousing passage; and

one or more flexible valve elements secured to said valve body andextending across said valve passage for blocking blood flow in a firstdirection through said valve passage whilst allowing blood flow in anopposing second direction through said valve passage;

said valve component being configurable between a valve collapsed statefor delivery to said housing passage via catheter, when said housingbody is in said housing expanded state following delivery to the nativevalve orifice, and an expanded state to engage said housing componentand/or structure of said heart to fix said valve body at least partiallywithin said housing passage.

The valve body is typically configured to be located and fixed whollywithin the housing passage.

In various embodiments, the housing body comprises a housing body frameformed of one or more elongate elastic housing body frame elements. Thehousing body may further comprise a flexible housing wall fixed to thehousing body frame and extending about the housing passage.

In some embodiments, the housing body is substantially cylindrical,whilst in other embodiments the housing body is tapered.

In various preferred embodiments, the housing passage is double-tapered,defining a housing passage neck portion located between opposing ends ofthe housing passage. In such embodiments the valve body is typicallyalso double-tapered, defining a valve body neck portion adapted toco-operate with the housing passage neck portion to secure the valvebody within the housing passage.

The valve body may comprise a valve body frame formed of one or moreelongate elastic valve body frame elements.

The valve component may comprise a stent valve, the valve body beingconfigured to be fixed at least partially within the housing passage byexpansion of the valve body.

The housing component may further comprise one or more flexibletemporary valve elements secured to the housing body and extendingacross the housing passage for inhibiting blood flow in a firstdirection through the housing passage whilst allowing blood flow in anopposing second direction through the housing passage prior to deliveryof the valve component.

In various embodiments, the prosthesis is an atrioventricular valveprosthesis for replacing an atrioventricular valve (that is, a mitralvalve or tricuspid valve). In particular, the prosthesis may be a mitralvalve prosthesis for replacing a mitral valve.

In certain embodiments, the housing component further comprises a skirtextending about a periphery of the housing body for inhibiting bloodflow in the first direction between the housing body and a wall of thenative valve orifice.

The housing body may be configured to be located with an end of thehousing adjacent to and communicating with the native valve orifice andthe skirt is located adjacent to the end of the housing body.

For atrioventricular valve applications, the housing componentpreferably includes an anchoring mechanism secured to the housing bodyand configured to engage native tissue of the heart. Typically, theanchoring mechanism is configured to engage native tissue of the heartoutside of the native valve orifice.

The anchoring mechanism may be configured to engage a wall of aventricle of the heart communicating with the native valve orifice.Alternatively or additionally, the anchoring mechanism is configured toengage a wall of an atrium of the heart communicating with the nativevalve orifice.

In certain embodiments, the anchoring mechanism includes a plurality ofprimary prongs secured to and spaced about the housing body. The primaryprongs are typically configured to engage native tissue of the heartoutside of the native valve orifice.

The primary prongs may each be secured to the housing body by one ormore legs extending from an end of the housing body.

The legs typically extend into a ventricle of the heart communicatingwith the valve orifice, the primary prongs being configured to engage awall of the ventricle and/or sub-valvular tissue, such as papillarytissue or the chordae tendineae, of the heart.

The anchoring mechanism may further comprise a plurality of secondaryprongs secured to and spaced about the housing body. The secondaryprongs may be located such that, in use, the secondary prongs arelocated on an opposing side of the native valve orifice to the primaryprongs.

In one embodiment, the valve component includes a collapsible anchordevice for anchoring the valve body to a septum of the heart and aflexible anchor line extending between the valve body and the anchordevice, the anchor device being collapsible for delivery via catheterwith the valve body.

In one or more embodiments, the prosthesis is a semilunar valveprosthesis for replacing a semilunar valve (that is, an aortic valve orpulmonary valve). In particular, the prosthesis may be an aortic valveprosthesis for replacing an aortic valve.

For semilunar valve applications, the housing component is typicallyconfigured to engage a wall of the native valve orifice to fix thehousing body in relation to the native valve orifice.

The housing component may comprise a generally tubular housing bodyformed of an elastically compressible material. The housing body may beintegrally formed of a polymeric material.

In a second aspect, the present invention provides a method of replacinga failing or failed heart valve of a patient, said method comprising thesteps of:

a) delivering a housing component of a heart valve prosthesis into, oradjacent to and in communication with, the native valve orifice of theheart valve to be replaced;

b) securing said housing component to structure of the heart so as tofix said housing component in relation to the native valve orifice;

c) delivering a valve component of said heart valve prosthesis at leastpartially into a housing passage defined by said housing component; and

d) securing said valve component at least partially into said housingpassage.

Typically, the valve component is delivered and secured wholly withinthe housing passage.

Typically, the housing component is delivered via catheter in acollapsed state and expanded into an expanded state within, or adjacentto and in communication with, the native valve orifice, thereby engagingstructure of the heart to fix said housing component in relation to thenative valve orifice. The valve component is delivered via catheter in acollapsed state and expanded into an expanded state within the housingpassage, thereby engaging the housing body and/or structure of the heartto fix the valve body within the housing passage.

The housing component may be secured to structure of the heart outsideof the native valve orifice.

The heart valve may be an atrioventricular valve, typically a mitralvalve.

For a mitral valve application, the method may further comprise the stepof creating a septal puncture in the inter-atrial septum of the heart,the housing component and the valve component each being deliveredpercutaneously via catheter through the venous system of the patient andthrough the septal puncture.

Alternatively, the method may further comprise the step of creating anapex puncture in the apex of the left ventricle of the heart, thehousing component and the valve component each being delivered viacatheter through the apex puncture.

The heart valve may be a semilunar valve, typically an aortic valve.

For an aortic valve application, the housing component and the valvecomponent may each be delivered percutaneously via catheter through thearterial system of the patient.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be described, byway of examples only, with reference to the accompanying drawingswherein:

FIG. 1 is a perspective view of a heart valve prosthesis according to afirst embodiment in a disassembled state;

FIG. 2 is a front elevation view of the heart valve prosthesis of FIG. 1in the disassembled state;

FIG. 3 is a schematic representation of the housing body and valve bodyof the heart valve prosthesis of FIG. 1 in a partly assembled state;

FIG. 4 is a schematic representation of the housing body and valve bodyof FIG. 3 in an assembled state;

FIG. 5 is a schematic cross-sectional front elevation view of a heartdepicting a catheter and guide wire advanced into the right atrium witha puncture formed in the inter-atrial septum;

FIG. 6 is a cross-sectional fragmentary view of a catheter with thehousing component of the heart valve prosthesis of FIG. 1 loadedtherein;

FIG. 7 is a schematic cross-sectional front elevation view of the heartof FIG. 5 with the housing component advanced to the end of thecatheter;

FIG. 8 is a schematic cross-sectional front elevation view of the heartof FIG. 5 with the housing in the expanded state adjacent the mitralvalve orifice;

FIG. 9 is a schematic cross-sectional front elevation view of the heartof FIG. 5 with the guide wire withdrawn from the housing component;

FIG. 10 is a schematic cross-sectional front elevation view of the heartof FIG. 5 with the valve component of the heart valve prosthesis of FIG.1 advanced toward the end of the catheter;

FIG. 11 is a cross-sectional front elevation view of the heart of FIG. 5with the heart valve prosthesis of FIG. 1 fully implanted;

FIG. 12 is a schematic cross-sectional front elevation view of a heartdepicting a catheter and guide wire advanced into the left ventriclethrough a puncture formed in the apex of the left ventricle;

FIG. 13 is a schematic cross-sectional front elevation view of the heartof FIG. 12 with the housing component advanced to the end of thecatheter;

FIG. 14 is a schematic cross-sectional front elevation view of the heartto FIG. 12 with the housing component in a partially expanded stateadjacent the mitral valve orifice;

FIG. 15 is a schematic cross-sectional front elevation view of the heartof FIG. 12 with the guide wire withdrawn from the housing component;

FIG. 16 is a schematic cross-sectional front elevation view of the heartof FIG. 12 with the valve component of the heart valve prosthesis ofFIG. 1 advanced towards the end of the catheter;

FIG. 17 is a schematic cross-sectional front elevation view of the heartof FIG. 12 with the heart valve prosthesis of FIG. 1 fully implanted;

FIG. 18 is a perspective view of a heart valve prosthesis according to asecond embodiment in a disassembled state;

FIG. 19 is a front elevation view of the heart valve prosthesis of FIG.18 in the disassembled state;

FIG. 20 is a perspective view of a heart valve prosthesis according to athird embodiment in a disassembled state;

FIG. 21 is a perspective view of a heart valve prosthesis according to afourth embodiment in the disassembled state;

FIG. 22 is a perspective view of a heart valve prosthesis according to afifth embodiment installed in a heart;

FIG. 23 is a perspective view of a heart valve prosthesis according to asixth embodiment in a disassembled state;

FIG. 24 is a perspective view of the housing component of a heart valveprosthesis according to a seventh embodiment;

FIG. 25 is a cross-sectional front elevation view of the housingcomponent of FIG. 24;

FIG. 26 is a schematic cross-sectional front elevation view of a heartdepicting the housing component of FIG. 24 advanced beyond the end of acatheter located in the ascending aorta;

FIG. 27 is a schematic cross-sectional front elevation view of the heartof FIG. 26 with the housing in the expanded state in the ascendingaorta;

FIG. 28 is a schematic cross-sectional front elevation view of the heartof FIG. 26 with the valve component of the heart prosthesis of the sixthembodiment advanced beyond the end of the catheter; and

FIG. 29 is a schematic cross-sectional front elevation view of the heartof FIG. 26 with the heart valve prosthesis of the sixth embodiment fullyimplanted.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 4 of the accompanying drawings, a firstembodiment of a heart valve prosthesis 100 is a two-component assembly,comprising a housing component 110 and a valve component 130. The heartvalve prosthesis 100 is described here in terms of a mitral valveprosthesis for replacing a failed or failing mitral valve, however theheart valve prosthesis is also applicable to other heart valvesincluding, in particular, the tricuspid valve.

The housing component 110 includes a housing body 111 that has a housingbody first end 111 a, a housing body second end 111 b, and a housingpassage 112 extending between the housing body first and second ends 111a, 111 b along a longitudinal housing axis 113. As will be discussedfurther below, the housing body 111 is configured to be located adjacentto and communicating with the native mitral valve orifice of the heartwith the housing body second end 111 b located within the left ventricleand the housing body first end 111 a located adjacent to andcommunicating with the mitral valve orifice, still located on the leftventricular side of the mitral valve orifice, but adjacent the leftatrium. In other embodiments discussed below, the housing body isconfigured to be located in the native mitral valve orifice with thehousing body first end located in the left atrium with the housing bodyextending through the mitral valve orifice. In still other embodiments,the housing body may be configured to be located on the left atrialside, adjacent to the native mitral valve orifice. Accordingly, thefirst end will hereinafter be referred to as the atrial end and thesecond end referred to as the ventricular end, although alternateterminology would be appropriate for applications in replacement ofheart valves other than the mitral valve.

The housing body 111 is here formed of a generally annular housing bodyframe 114 formed of a single elongate elastic housing body frame element115 configured in a sinusoidal or concertina type configurationextending annularly about the housing passage 112. Rather than beingformed as a single element, the housing body frame 114 could be formedof several elements joined together by welding, clips or other suitablemeans. The housing body frame element 115 is typically in the form of awire formed of a super elastic shape memory material. A particularlysuitable material is nitinol, a nickel-titanium alloy that is known foruse in catheter delivered prosthesis applications. Other suitableelastic metallic materials include stainless steel, other titaniumalloys and cobalt chromium molybdenum. Other suitable relatively rigidyet elastic metal alloys or non-metallic materials may be utilised asdesired. The wire forming the housing body frame 115 will typically havea diameter of the order of 0.3 mm to 0.4 mm, however wire of alternatediameters is also envisaged. Rather than being formed of wire, thehousing body frame 114 could be cut from a cylindrical tube of material,typically a super elastic shape memory alloy such as nitinol. The tubecould be cut by laser to provide a largely open unitary frame structurewhich could be subsequently heat shaped to tailor the cross-section ofthe housing body along its length.

The housing body 111 also has a flexible housing wall 116 that is fixedto the housing body frame 114 and extends about the housing passage 112.The housing wall 116 may be formed of a suitable flexible biologicalmaterial, such as pericardial material. Alternatively, the housing wall116 may be formed of any suitable flexible non-biological material, suchas, for example, silicone, polyester or dacron. The housing wall 116will typically be fixed to the housing body frame 114 by suturing. Thehousing wall 116 serves to enclose the housing passage 112, inhibitingleakage through the housing body frame 114.

The housing component 110 further preferably includes a flexible skirt117 extending about a periphery of the housing body 111 for inhibitingblood flow in a first direction from the left ventricle into the leftatrium.

For configurations where the housing body 111 is intended to be locatedadjacent to the native mitral valve orifice on the ventricular side,rather than within the orifice, the flexible skirt 117 is located at thehousing body atrial (i.e., first) end 111 a such that, in use, it willengage and seal with tissue surrounding the valve orifice on theventricular side, as will be discussed below.

In configurations where the housing body 111 is intended to be locatedon the atrial side of the native mitral valve orifice, the flexibleskirt will generally be located at the housing body ventricular (i.e.,second) end 111 b such that, in use, it will engage and seal with tissuesurrounding the valve orifice on the atrial side. For configurationswhere the housing body is intended to extend through the native mitralvalve orifice, the flexible skirt may be located on either side of thenative valve orifice in use.

The flexible skirt 117 will typically be formed of the same material asthe housing wall 116. The flexible skirt 117 and housing wall 116 willalso typically be sutured to one another. It is also envisaged that theflexible skirt may be reinforced with wire or any of various other formsof reinforcement so as to provide the skirt with some degree ofstiffness.

The housing component 110 also includes an anchoring mechanism securedto the housing body 111. Here the anchoring mechanism includes aplurality of primary prongs 118 secured to and spaced about the housingbody 111. The primary prongs 118 are here each secured to the housingbody 111 by one or more legs 119 extending from the housing bodyventricular (i.e. second) end. The primary prongs 118 are thushereinafter described as ventricular prongs 118. The ventricular prongs118 are here arranged in two sets of three individual prongs 118 formedby bending the ends of each of the legs 119 so as to project radiallyoutwardly and longitudinally back toward the housing body 111. Theventricular prongs 118 are thus configured to engage native tissuestructure of the heart outside of the native valve orifice, rather thanrelying on fixation to the delicate, thin tissue constituting the mitralvalve orifice wall. In the particular arrangement depicted, the legs 119longitudinally offset the ventricular prongs 118 from the housing body111 such that, in use, the ventricular prongs engage the wall of theleft ventricle and/or subvalvular tissue, such as papillary muscletissue or the chordae tendineae, as will be discussed below. Theventricular prongs 118 and legs 119 are formed of a super elastic shapememory material in wire form, typically the same as the housing bodyframe element 115.

It is envisaged, however, that the prongs might be configured to engagethe mitral valve orifice wall. Whilst the mitral valve orifice wall isgenerally not capable of sustaining any significant radial forces asmight be applied by a stent, it generally will be capable of sustainingpoint anchor loads as may be applied by the prongs. The ventricularprongs 118 may be in the form of hooks or barbs. In place of the prongs,the anchoring mechanism may be in any of various alternate formsincluding clips, clamps, staples or adhesives. For embodimentsconfigured to replace other heart valves, particularly the aortic valveor pulmonary valve, it is envisaged that the housing body might be in aradially expandible stent form that directly engages the native orificewall to fix the housing component in relation to the valve orifice.

The entire housing component 110 is elastically collapsible from astable expanded state, as depicted in FIGS. 1 and 2, into an unstablecollapsed state extending along the housing longitudinal axis 113 toallow delivery of the housing component 110, typically percutaneously,by catheter.

The entire surface of the housing component 110 would typically becoated with a suitable coating to inhibit, or at least reduce the effectof, thrombus formation. Particularly suitable coatings for applicationto the housing body frame 114 include polyester coatings, texturedmetallic coatings, heparin based coatings, diamond-like carbon coatings,parylene coatings and fluoropolymer coatings such aspolytetrafluoroethylene. Textured metallic coatings may be applied inthe form of sintered nitinol or titanium and serve to add texture to thesurface, helping to ensure any thrombus formed does not break free intothe bloodstream. Such textured surfaces also promote tissue ingrowth tothe foreign housing body frame 114. The same coating may be applied tothe ventricular prongs 118 and legs 119. Coatings that would beparticularly suitable for application to the housing wall 116 andflexible skirt 117 to inhibit thrombus formation include heparin basedcoatings, parylene coatings and fluoropolymer based coatings such aspolytetrafluoroethylene.

The valve component 130 includes a valve body 131 that has a valve bodyatrial (i.e., first) end 131 a, a valve body ventricular (i.e., second)end 131 b and a valve passage 132 extending between the valve bodyatrial and ventricular ends 131 a, 131 b along a longitudinal valve axis133. In the arrangement depicted, the valve body 131 is formed of avalve body frame 134 formed of three elongate elastic valve body frameelements 135. Each of the valve body frame elements 135 is in thegeneral form of an arch formed of a wire of super elastic shape memorymaterial, typically the same as that of the housing body frame element115. Each valve body frame element 135 has its opposing ends 135 blocated at the valve body ventricular end 131 b and its vertex 135 alocated at the valve body atrial end 131 a. The ends 135 b of each valvebody frame element are secured to each other, typically by welding orcrimping, however other suitable metals are also envisaged. It is alsoenvisaged that the valve body frame could be formed of a single valvebody frame element, such that only the opposing ends of the single valvebody frame element would be sewed to each other.

A flexible valve element 136 is secured to each of the valve body frameelements 135, typically by suturing. The valve elements 136 may beformed of a suitable flexible biological material, such as pericardialmaterial including bovine pericardium or kangaroo pericardium. The valveelements 136 may alternatively be formed of a suitable flexiblenon-biological material. The valve elements 136 are secured to the valvebody frame elements 135 and configured such that they extend across thevalve passage 132 in a manner that they block blood flow in a firstdirection through the valve passage 132 from the valve body ventricularend 131 b toward the valve body atrial end 131 a, whilst allowing bloodflow in an opposing second direction. The valve elements 136 each extendlaterally beyond their respective valve body frame element 135 towardthe valve body atrial end 131 a, with adjacent valve elements 136overlapping or being sutured to form a continuous valve leafletstructure about the circumference of the valve body 131 at the valvebody atrial end 131 a.

The entire valve component 130 is elastically collapsible from a stableelastically expanded state, as depicted in FIGS. 1 and 2, into anunstable collapsed state extending along the valve longitudinal axis 133to allow delivery of the valve component 130, typically percutaneously,by catheter.

Forming the heart valve prosthesis 100 as two separate percutaneouslydeliverable components allows for use of a smaller catheter than wouldotherwise be possible if the housing and valve were formed as a singlecomponent. Forming the heart valve prosthesis as two separate componentsalso enables provision of a relatively simple (and thereby inexpensive)valve component which can be discarded if biological material formingthe valve elements has reached its shelf life, whilst retaining thehousing component, which might employ non-biological material for theflexible housing wall 116 and flexible skirt 117, thereby providing itwith a longer shelf life. The two component prosthesis also enablesutilisation of commonly known stent based aortic valves as the valvecomponent for a mitral valve prosthesis. Handling and preservation ofthe simpler valve component 130 and securing of the valve elements tothe valve body by the bedside may also be simplified. Further, the twocomponent prosthesis potentially allows for the placement of theprosthesis in different locations of the heart, including differentsized heart valve orifices, by altering the size or configuration of thehousing component only, using a common valve component.

With particular reference to FIGS. 3 and 4, both the housing body 111and the valve body 131 are double-tapered providing an asymmetrichourglass-type shape. The double-tapered shape of the housing body 111provides a double-tapered housing passage 112. The housing passage 112has a reduced neck portion 120 located between the housing body atrialend 111 a and housing body ventricular end 111 b. The valve body 131also has a neck portion 140 located between the valve body atrial end131 a and valve body ventricular end 131 b. The housing passage 112 andvalve body 131 are sized such that the double-taper acts to secure thevalve body 131 within the housing passage 112, with the valve passageneck portion 140 co-operating with the housing body neck portion 120.Alternatively, the housing passage 112 and valve body 131 could besubstantially cylindrical or singularly tapered, and be provided withalternate means for securing the valve body 131 within the housing body111, such as connectors, prongs or other suitable fastening means.

Replacement of a failed or failing mitral valve by implantation of themitral valve prosthesis 100 of the first embodiment described aboveusing a percutaneous venous approach will now be described withreference to FIGS. 5 through 11. The venous system of the patient to betreated is firstly accessed by a puncture, typically in the groin area,accessing the femoral vein. Access to the venous system mightalternatively be made via other large peripheral veins such as thesub-clavian or jugular veins. The femoral vein is, however, preferredgiven the compressibility of the femoral vein once a catheter is removedfrom the patient to achieve haemostasis.

Referring to FIG. 5, a guide wire 1, typically having a diameter ofapproximately 0.85 mm to 1.7 mm, is inserted through the puncture andalong the femoral vein and via the inferior vena cava 11 to the rightatrium 12 of the patient's heart 10. If additional steadying of theguide wire 1 is desired, a snare may be introduced to the heart 10through an arterial approach from the left or right femoral artery,aorta and aortic valve. The snare will then engage a J-tip on the end ofthe guide wire 1 and draw the end of the guide wire 1 through thearterial system to the exterior of the patient so that opposing ends ofthe guide wire 1 may be steadied.

A catheter 2, typically having a diameter of about 20 to 24 French (6.7mm to 8.0 mm) is then advanced over the guide wire 1 and into the rightatrium 12. A puncture 13 is then made in the inter-atrial septum 14using conventional equipment advanced by the catheter 2 in a knownmanner. The guide wire 1 and catheter 2 are then further advancedthrough the septal puncture 13 and into the left atrium 15.

Referring to FIG. 6, the housing component 110 of the mitral valveprosthesis 100 is collapsed and fed into the catheter 2 with the housingbody atrial end 111 a trailing the housing body ventricular end 111 b.The housing component 110 is then delivered percutaneously by firstbeing advanced along the guide wire 1 to the leading end 2 a of thecatheter as depicted in FIG. 7. The leading end 2 a of the catheter 2extends through the native mitral valve orifice 16 and into the leftventricle 17, carefully positioning the housing component 110 (thatremains collapsed inside the catheter 2) in the left ventricle 17adjacent the mitral valve orifice 16. The failed or failing nativemitral valve leaflets will typically be left in place. The catheter 2 isthen withdrawn whilst leaving the guide wire 1 and housing component 110in place, such that the housing component 110 is allowed to expand intothe left ventricle 17, as depicted in FIG. 8. The ventricular prongs 118engage the papillary muscles 18 within the left ventricle 17 and/or thewall of the left ventricle 17, thereby securing the housing body 111 inrelation to the mitral valve orifice 16. The ventricular prongs 118 mayalternatively or additionally engage other subvalvular tissue of theheart, particularly the chordae tendineae. The ventricular prongs 118and legs 119 may also assist in preventing complete collapse of the leftventricle, where opposing walls make contact in what is termed“obliteration”, as the ventricular prongs 118 will act to prop the leftventricle 17 open to some extent in a stent-like manner. This may bebeneficial to patients suffering diastolic heart failure. To achievethis effect, the legs 119 should be of sufficient structural stiffnessto provide the desired supporting effect.

At this stage, the housing component 110 remains attached to the guidewire 1 by way of a tether 3 that allows for some re-positioning of thehousing body 111 in relation to the mitral valve orifice 16 and, ifgreater adjustment is required, allows the catheter 2 to be advancedback over the housing component 110, re-collapsing the housing component110 into the catheter 2, for further re-positioning as required. Oncethe housing component 110 is in the correct position, the tether 3 isdetached from the housing component 110 and the guide wire 1 withdrawnback into the catheter 2, as depicted in FIG. 9.

Referring to FIG. 10, the valve component 130 of the heart valveprosthesis 100 is next collapsed and loaded into the catheter 2, withthe valve body atrial end 131 a trailing the valve body ventricular end131 b.

The valve component 130 is advanced along the guide wire 1 toward thesecond end 2 a of the catheter which itself is advanced to the atrialend of the housing passage 112 within the housing component 110, readyfor deployment of the valve component 130. Once the collapsed valvecomponent 130 is located in the appropriate position within the housingpassage 112, the catheter 2 is withdrawn, allowing the valve component130 to elastically expand into engagement with the housing body frame114 of the housing body 111, securing the valve component 130 to thehousing body 111 with the valve passage 132 extending along the housingpassage 112. The catheter 2 and guide wire 1 are then withdrawn from thepatient, leaving the assembled heart valve prosthesis 100 in position asdepicted in FIG. 11 effectively replacing the native mitral valve. The(ineffective) native mitral valve would typically be left in place, withthe native valve leaflets retained on the outside of the housingcomponent 110 where they may assist in preventing paravalvular leakageduring ventricular systole. Blood flow from the left atrium into theleft ventricle during atrial systole is provided for through the valveelements 136, whilst the same valve elements 136 prevent back flow fromthe left ventricle 17 into the left atrium 15 during ventricularsystole. Back flow from the left ventricle 17 into the left atrium 15from outside of the housing component 110 is also inhibited by virtue ofthe flexible skirt 117 which effectively seals against the periphery ofthe mitral valve orifice 16 against any back flow when the leftventricle 17 contracts and pressurizes during ventricular systole.

The entire procedure may be performed under the guidance of fluoroscopytransthoracic and transesophageal echocardiography in a known manner.

In a modification of the procedure described above, a larger firstcatheter (typically about 24 French) is first advanced over the guidewire 1 to a position extending through the native mitral valve orifice16, displacing the native mitral valve leaflets. A smaller catheter 2(typically 20-21 French) is then advanced through the first catheter,delivering the housing component 110. Once the second catheter 2 is inposition ready for release of the housing component 120, the firstcatheter is withdrawn slightly, allowing the housing component 110 to beexpanded into position. The valve component 130 is then delivered eitherthrough the same second catheter 2 or another catheter, again advancingthrough the first catheter.

Replacement of a failed or failing mitral valve by implantation of themitral valve prosthesis 100 of the first embodiment using an alternatetrans-apical approach will now be described with reference to FIGS. 12through 17. This method provides more direct access to the leftventricle 17 of the patient's heart 10 via the apex 19 of the leftventricle 17. Access to the apex 19 of the left ventricle 17 may beprovided either surgically or percutaneously. In a surgical procedure, alimited surgical incision may be first made in the precordial region ofthe thorax, providing direct and visual access to the exterior of theapex 19 of the left ventricle 17. Alternatively, for a percutaneousprocedure, a needle puncture of the precordial region of the thorax maybe made and the region is then dilated by way of a balloon catheter soas to provide access to the exterior of the apex 19 of the leftventricle 17.

Referring to FIG. 12, the left ventricle 17 is then accessed by creatinga puncture 20 in the apex 19 of the left ventricle 17. For the surgicalprocedure, the puncture 20 may be created by way of direct surgicalincision. For the percutaneous procedure, the puncture 20 may be createdby way of conventional cutting equipment advanced by catheter. A guidewire 1, typically having a diameter of approximately 0.85 mm to 1.7 mm,is inserted directly through the puncture 20 in the surgical procedureor following balloon dilation of the area in the percutaneous procedure.

A catheter 2, typically having a diameter of about 20 to 24 F (6.7 mm to8.0 mm) is then advanced over the guide wire 1 and into the leftventricle 17 through the puncture 20, as depicted in FIG. 12.

Referring to FIG. 13, the housing component 110 of the mitral valveprosthesis 100 is collapsed and fed into the catheter 2 with the housingbody ventricular end 111 b trailing the housing body atrial end 111 a.The housing component is delivered to the left ventricle 17 by beingadvanced along the guide wire 1 to the leading end 2 a of the catheter2. The leading end 2 a of the catheter 2 is carefully positioned withinthe left ventricle 17 adjacent the mitral valve orifice 16, ready fordeployment of the housing component 110. The failed or failing nativemitral valve leaflets would typically be left in place and may bedisplaced from a position extending across the mitral valve orifice 16by balloon dilation prior to delivery of the housing component 110 ifdesired.

The catheter 2 is then partly withdrawn whilst leaving the guide wire 1and the housing component 110 in place, allowing the housing body 111 ofthe housing component 110 to expand as depicted in FIG. 14. At thisstage, the ventricular prongs 118 are constrained by a restrainingdevice 4 that is advanced with the housing component 110 alongside theguide wire 1. The restraining device 4 may be in the form of a wireclamp, wire lasso or similar formed on the end of an auxiliary wire 4 a.The position of the housing component 110 is then fine tuned as requiredto position the housing body atrial end 111 a adjacent the mitral valveorifice 16 providing communication with the housing passage 112. Thecatheter 2 is then further withdrawn and the restraining device 4released, as depicted in FIG. 15, thereby allowing the housing component110 to fully expand such that the ventricular prongs 118 engage the wallof the left ventricle 17 and/or papillary muscles 18 and/or othersubvalvular tissue such as the chordae tendineae of the heart.

Referring to FIG. 16, the valve component 130 of the heart valveprosthesis 100 is next collapsed and loaded into the catheter 2, withthe valve body ventricular end 131 b trailing the atrial end 131 a.

The valve component 130 is advanced along the guide wire 1 towards theleading end 2 a of the catheter 2 which itself is advanced to theventricular end of the housing passage 112 within the housing component110, ready for deployment of the valve component 130. Once the collapsedvalve component 130 is located in the appropriate position within thehousing passage 112, the catheter 2 is withdrawn, allowing the valvecomponent 130 to elastically expand into engagement with the housingbody frame 114 of the housing body 111, securing the valve component 130to the housing body 111. The catheter 2 and guide wire 1 are thenwithdrawn from the left ventricle 17. Referring to FIG. 17, the puncture20 in the apex 19 is then sealed by deploying a plug 150 in a knownmanner. The plug 150 will typically be deployed from the catheter 2 andmay be in the form of a collapsible body formed of nitinol or any othersuitable material. The catheter 2 and guide wire 1 are then fullywithdrawn from the patient, leaving the assembled heart valve prosthesis100 in position as depicted in FIG. 17, replacing the native mitralvalve. The trans-apical approach described allows for more direct accessto the mitral valve orifice than the venous approach described above inrelation to FIGS. 6 to 11 which may provide access problems as a resultof the tortuous nature of the access path through the venous system.

Referring to FIGS. 18 and 19 of the accompanying drawings, a secondembodiment of a percutaneous heart valve prosthesis 200 is depicted.With the heart valve prosthesis 200, the valve component 130 isidentical to that of the heart valve prosthesis 100 of the firstembodiment described above.

The housing component 210 is similar to the housing component 110 of thefirst embodiment. Accordingly like or equivalent features adopt the samereference numerals as the housing component 110 of the first embodiment,increased by 100. A similar reference numeral system is applied for eachof the hereinafter described embodiments. The housing component 210 hasa housing body 211 that is intended to be located within the nativemitral valve orifice 16 with the housing body atrial end 211 a locatedwithin the left atrium 15 and the housing body ventricular end 211 blocated within the left ventricle 16. Accordingly, the flexible skirt217 is located between the housing body atrial and ventricular ends 211a, 211 b such that, in use, the flexible skirt 217 engages the nativetissue surrounding the valve orifice 16 on the ventricular side. In thehousing component 210, the anchoring mechanism further comprises aplurality of secondary or atrial prongs 221 secured to and spaced aboutthe housing body atrial end 211 a. Here the atrial prongs 221 are eachsecured to the housing body frame 214 by way of arms 222 that are eachformed as a bent extension of individual housing body frame elements 215of the housing body frame 214. The atrial prongs 221 extend over thedelicate thin tissue immediately surrounding the valve orifice 16 so asto engage the muscular walls of the left atrium outside the valveorifice 16. The ends of the atrial prongs 221 are bent back to formgenerally radially inwardly directed hooks. The atrial prongs 222 assistin securing the housing body 211 in relation to the valve orifice, andparticularly assist in preventing the housing body 211 from migratinginto the left ventricle 17. The housing component 210 is otherwisesubstantially identical to the housing component 110 of the firstembodiment.

Referring to FIG. 20, a third embodiment of a percutaneous heart valveprosthesis 300 is depicted. In this embodiment, the housing component110 is identical to that of the heart valve prosthesis 100 of the firstembodiment, whilst the valve element 330 is in the form of apercutaneously deliverable expandible stent valve. The valve body 331 ofthe valve component 330 may be either self-expanding or balloonexpandible. The radial load applied to the housing body frame 114 whenthe valve body 331 is expanded within the housing passage 112 of thehousing component 110 secures the valve body 331 to the housing body.The radial load is carried by the housing body 111 rather than the thin,delicate wall of the mitral valve orifice 16 as is the case with stentvalves implanted directly into the mitral valve orifice 16. The valvebody 331 is configured such that the valve body atrial end 331 aprotrudes beyond the housing body atrial end 111 a and into the leftatrium. The valve body 331 is of a generally tapered shape, with thevalve body atrial end 331 a being broader than the valve bodyventricular end 331 b such that the enlarged diameter of the valve bodyatrial end 331 a expands into the left atrium 15, assisting inpreventing movement of the heart valve prosthesis 380 downwards into theleft ventricle. One or more flexible valve elements (not depicted) aresecured to the valve body 331 and extend across the valve passage 332for blocking blood flow to the valve passage 332 from the valve bodyventricular end 331 b toward the valve body atrial end 331 a

Referring to FIG. 21, a fourth embodiment of a heart valve prosthesis400 again has the same housing component 110 as the heart valveprosthesis 100 of the first embodiment. In this embodiment, the valvecomponent 430 is in the form of a percutaneously deliverable cylindricalstent valve. The valve body 431 is configured to be locatedsubstantially wholly within the housing passage 112 of the housingcomponent 110 and may be secured to the housing body 111 solely byradial pressure following either balloon or self-expansion of the valvebody 431. Alternatively, both the stent valve body 431 and housing body111 could be provided with a double-taper in the same manner as depictedin FIGS. 3 and 4 to secure the valve body 431 within the housing passage112. Alternatively, or additionally, the valve body 431 could be securedto the housing body 111 by clips or other suitable fasteners. One ormore flexible valve elements (not depicted) are secured to the valvebody 431 and extend across the valve passage 432 for blocking blood flowthrough the valve passage 432 from the valve body ventricular end 431 btoward the valve body atrial end 431 a.

Referring to FIG. 22, a fifth embodiment of a percutaneous heart valveprosthesis 500 is depicted in an assembled state installed in a heart10. The heart valve prosthesis 500 has a housing component 110 identicalto the housing component of the heart valve prosthesis 100 of the firstembodiment, and the housing component 110 is thus implanted in the samemanner as described above. The valve component 530 is also identical tothe valve component 130 of the first embodiment, with the addition of ananchor device 541 and flexible anchor line 542. The anchor line 542connects the anchor device 541 to the valve body frame of the valvecomponent 530. The anchor device 541 comprises an elasticallycollapsible anchor frame formed of elongate anchor frame elements,typically formed of the same material as the frame elements of thehousing body and valve body. The anchor device 541 is elasticallycollapsible from a stable substantially flat plate-like configuration(as shown in FIG. 22) to an unstable elongate configuration for locationwithin the catheter 2 during percutaneous delivery of the valvecomponent 530. The anchor device 541 may conveniently be of the generalform of the anchor device disclosed in International PCT Publication No.WO 2005/087140 to the present applicant, the entire contents of whichare incorporated herein by cross-reference.

During percutaneous delivery of the valve component 530, the anchordevice 541 is released from the end of the catheter 2 after release ofthe valve body 531 with the end of the catheter 2 retracted in the rightatrium 12 adjacent the inter-atrial septum 14. Upon release of theanchor device 541 from the catheter 2, the anchor device 541 expands andacts as an anchor against the inter-atrial septum 14, anchoring thevalve component 530 (and by virtue of the valve component's 530 fixationto the housing component 110, the entire heart valve prosthesis 500)against migration deeper into the left ventricle 17. It is alsoenvisaged that the anchor device might alternately be permanentlyattached to the housing component 110, however, this would result in asignificantly more complicated delivery procedure, given that the anchordevice would tend to block the septal puncture 13, preventing deliveryof the valve component through the same septal puncture. It is furtherenvisaged that the anchor device 541 might be separate to both thehousing component and valve component, being percutaneously delivered tothe heart separately and following delivery of the valve component. Theanchor device would then be secured to either the housing component orvalve component within the heart. The anchor line 542 could either bedelivered with the anchor device 541 and subsequently secured to thehousing element/valve element or alternately the anchor line 542 couldbe delivered with the housing element/valve element and subsequentlysecured to the anchor device 541.

Referring to FIG. 23, a sixth embodiment of a percutaneous heart valveprosthesis 100′ is depicted in a disassembled state. The heart valveprosthesis 100′ is identical to that of the first embodiment describedabove and depicted in FIG. 1 apart from the inclusion of a plurality offlexible temporary valve elements 122 in the housing component 110′secured to the housing body frame elements 115 so as to extend acrossthe housing passage 112. The temporary valve elements 122 are configuredto inhibit blood flow in the first direction through the housing passage112 from the housing body ventricular end 111 b towards the housing bodyatrial end 111 a, whilst allowing blood flow in the opposing seconddirection. The temporary valve elements 122 serve to inhibitregurgitation of blood from the left ventricle 17 back into the leftatrium 15 during the implantation procedure, following location of thehousing component 110′ until subsequent delivery of the valve component130. Given that the temporary valve leaflets 122 are thus only operativefor a relatively short time, they may be quite simple in configurationand be made from simple flexible synthetic materials. The prosthesis100′ may be implanted utilising any of the procedures discussed above,with the valve component 130 simply pushing aside the temporary valveleaflets 122 when expanded into position within the housing passage 112.The temporary valve leaflets 122 remain sandwiched between the valvecomponent 130 and the housing wall 116.

In a further embodiment (not depicted) the housing component of thepercutaneous heart valve prosthesis has a housing body in the form of anexpandable stent structure having a central portion configured to belocated within the native mitral valve orifice, an atrial end portionconfigured to be located within the left atrium and an opposingventricular portion configured to be located within the left ventricle.When located in position, the central portion of the housing body isonly partly expanded to a diameter not exceeding that of the nativemitral valve orifice, so as not to place any significant radial pressureloads on the wall of the valve orifice. The opposing atrial andventricular portions of the housing body are further expanded beyond thediameter of the valve orifice so as to effectively “sandwich” the wallof the native mitral valve orifice between the atrial and ventricularportions of the housing body, thereby fixing the housing body inrelation to the valve orifice. Any of various forms of the valvecomponent could then be fixed within the housing passage defined by thehousing body.

Various other forms of securing the various heart valve prosthesesdescribed above are also envisaged. For example, the valve component maybe configured with ventricular or atrial prongs to assist in directlyfixing the valve component to the structure of the heart. The valve bodyand housing body may also be tapered so as to act as a plug that cannotmigrate through the heart valve orifice, with an anchoring mechanismbeing located on that side of the valve orifice through which thenarrower end of the housing body and valve body protrude. For example,with the heart valve prosthesis 500 of the fifth embodiment describedabove in relation to FIG. 22, the atrial end of both the valve body andhousing body could be narrower than the valve orifice and theventricular end of the valve body and housing body, with the anchordevice 541 and anchor line 542 acting to retain the heart valveprosthesis partly within the heart valve orifice in a plugged state. Insuch an arrangement, the flexible skirt 117 of the housing componentwould be located partway between the atrial and ventricular ends of thehousing body. It is also envisaged that the valve component may also beprovided with a flexible skirt similar, and additional to or in placeof, the flexible skirt 117 of the housing component 110.

Whilst the various two component heart valve prosthesis described aboveeach relate to a mitral valve prosthesis, the two component prosthesisconcept is also applicable to each of the remaining heart valves, beingthe tricuspid valve and the semilunar valves (that is, the pulmonaryvalve and the aortic valve).

A seventh embodiment of a two component heart valve prosthesis, in theform of an aortic heart valve prosthesis 600, and an associated aorticheart valve replacement procedure will now be described with referenceto FIGS. 24 through 29.

Referring firstly to FIGS. 24 and 25, the housing component 610 of theaortic valve prosthesis 600 comprises a generally tubular housing body611 that has a housing body first end 611 a, a housing body second end611 b and a housing passage 612 extending between the housing body firstand second ends 611 a, 611 b along a longitudinal housing axis 613. Thehousing passage 612 is double tapered, with the housing passage 612being wider at the housing body first and second ends 611 a, 611 b thanin the central neck region 620 of the housing passage 612. This doubletapering of the housing passage 612 assists in positioning and retainingthe valve component 630 as will be discussed further below. The housingcomponent 610 is sized and shaped to be located within the ascendingaorta 22 of the patient's heart 10 in the position of the native aorticvalve.

The housing body 611 is here in the form of an elastically compressible,flexible biocompatible material. Particularly preferred materials forconstruction of the housing body 611 include silicone and otherbio-stable polymers. Alternatively, the housing body 611 could be in theform of a covered wire mesh stent. Persons skilled in the art willappreciate that many other suitable materials may alternatively beutilised. The housing component 610 is elastically collapsible from astable expanded state, as depicted in FIGS. 24 and 25, into an unstablecollapsed state extending along the housing longitudinal axis 613 toallow delivery of the housing component 610, typically percutaneously,by catheter. The housing component 610 may be forced into the unstablecollapsed state for delivery by the application of radial compressiveforce. The housing component 610 may include a marker 623, in the formof a small metallic ring. The marker 623 may be integrally moulded withthe housing body 612 or otherwise inserted into the housing passage 611prior to implantation. The marker 623 extends about the housing passage612 and is adapted to be visible on fluoroscopic or X-ray imagingequipment so as to facilitate doctors and surgeons identifying theposition, orientation and location of the housing component 610, whichmay be otherwise invisible to these imaging techniques when the housingbody 611 is formed of a polymeric material.

In the particular arrangement depicted in FIGS. 28 and 29, the valvecomponent 630 comprises a tubular valve body 631 that has a valve bodyfirst end 631 a, a valve body second end 631 b, and a valve passage 632extending between the valve body first and second ends 631 a, 631 balong a longitudinal valve axis. In the arrangement depicted, the valvebody 631 is formed of a valve body frame 534 that has a stent structureformed of elongate elastic valve body frame elements 635. The valve bodyframe elements 635 are each typically formed of a wire of super elasticshape memory material such as nitinol, stainless steel, other titaniumalloys and/or cobalt, chromium, molybdenum. Other suitable relativelyrigid yet elastic metal alloys or non-metallic materials mayalternatively be utilised as desired. The valve body frame elements 635are generally formed with a diamond pattern as is typical with stentstructures.

A plurality of flexible valve elements 636 are secured to the valve bodyframe elements 635, typically by suturing. Rather than being secureddirectly to the valve body frame elements 635, the valve elements 636may be secured to a sub-frame of the valve body frame 634 formed ofthree elongate elastic elements that are each formed into an arch andformed of a wire of superelastic shape memory material, typically beingthe same as that of the valve body frame elements 635. The sub-frame maybe generally of the same form as the housing body frame 134 of the valvecomponent 130 of the mitral valve prosthesis 100 of the firstembodiment. The sub-frame in this case would be secured to the valvebody frame 634, typically by suturing.

The valve elements 636 may again be formed of a suitable flexiblebiological material, such as pericardial material including bovinepericardium or kangaroo pericardium. Alternatively the valve elements636 may be formed of a suitable flexible non-biological material. Thevalve elements 636 are configured such that they extend across the valvepassage 632 in a manner that they block blood flow in a first directionto the valve passage 632 from the valve body second end 631 b towardsthe valve body first end 631 a, whilst allowing blood flow in anopposing second direction. The entire valve component 630 is collapsiblefrom a stable expanded state into a collapsed state extending along thevalve longitudinal axis 633 to allow delivery of the valve component630, typically percutaneously by catheter. The stent structure of thevalve body frame 634 may be elastically collapsible, such that it isself-expanding when released, or may otherwise be expandable by balloon.

The valve component 630 may alternatively be of the same construction asthe valve component 130 described above in relation to the firstembodiment depicted in FIGS. 1 and 2, or may take any of various otherforms including that of the valve component 430 of the heart valveprosthesis 400 of the fourth embodiment described above in relation toFIG. 15.

Replacement of a failed or failing aortic valve by implantation of theaortic valve prosthesis 600 of the sixth embodiment above using apercutaneous arterial approach will now be described with reference toFIGS. 26 through 29. The arterial system of the patient to be treated isfirstly accessed by a puncture providing access to the femoral artery.

Referring to FIG. 26, a guide wire 1, typically having a diameter ofapproximately 0.85 mm to 1.7 mm, is inserted through the puncture andadvanced along the femoral artery to the descending aorta, through theaortic arch 21 and into the ascending aorta 22. A catheter 2, typicallyhaving a diameter of about 20 to 24 F (6.77 mm to 8.0 mm) is thenadvanced over the guide wire 1 and into the ascending aorta 22. Thehousing component 610 of the aortic valve prosthesis 600 is radiallycompressed into its collapsed state and fed into the catheter 2 with thehousing body second end 611 b trailing the housing body first end 611 a.The housing component 610 is then delivered percutaneously by beingadvanced along the guide wire 1 through the catheter 2. A restrainingdevice 5 at the leading end of the guide wire 1 restrains the housingcomponent 610 in its radially compressed and collapsed state as theguide wire 1 is further advanced beyond the leading end 2 a of thecatheter towards the lower end of the ascending aorta 22 which forms thenative aortic valve orifice 23. The restraining device 5 is releasedonce the housing component 610 is in position with the housing bodyfirst end 611 a located adjacent the lower end of the ascending aorta 22and the housing body second end 611 b extending towards the aortic arch21. The marker 623 assists in ensuring correct placement.

Once the housing component 610 is released, it elastically expands intoits expanded state, engaging the walls of the ascending aorta 22 so asto secure the housing component 610 within the ascending aorta 22 asdepicted in FIG. 27. Radial expansion of the housing component 610 opensthe housing passage 612. The radial expansion of the housing component610 also presses the native valve leaflets against the wall of theascending aorta 22. The elastic nature of the housing body 611 providesfor an effective seal between the housing body 611 and the wall of theascending aorta 22, thereby eliminating paravalvular leaks.

Referring to FIG. 28, the valve component 630 is next collapsed into itscollapsed state and fed into the catheter 2 with the valve body secondend 631 b trailing the valve body first end 631 a. The valve component630 is advanced along the guide wire 1 towards the leading end 2 a ofthe catheter 2. The valve component 630 is again restrained by therestraining device 5 as the valve component 630 is advanced beyond theleading end 2 a of the catheter and into the housing passage 612 of thehousing component 610. The valve component 630 is advanced into itsappropriate position within the housing passage 612. This position maybe conveniently determined utilising the marker 623 of the housingcomponent 610. A further marker may be provided on the valve component630 if desired, although the valve body 631 will generally already bevisible on fluoroscopic or X-ray imaging equipment, given that it isformed of metallic wire. The valve component 630 is expanded into itsexpanded state with the valve body first end 631 a being located towardsthe housing body first end 611 a and the valve body second end 631 blocated towards the housing body second end 611 b.

If the valve body 631 is of a self-expanding form, release from therestraining device 3 will result in the valve component self-expandinginto engagement with the wall of the housing body 611. Alternatively,the valve body 631 may be expanded by balloon catheterisation if thevalve body is of a non-self-expanding configuration. It is alsoenvisaged that, in configurations where the shape memory characteristicsof the nitinol wire forming the valve body frame 634 have been utilisedto collapse the valve body 631 for delivery by catheter, the restrainingdevice 5 may apply heat to the valve body frame 634 so as to heat thevalve body frame elements 635 and thereby radially expand the valve body631 into its stable expanded state.

When the valve body 631 is expanded, engaging the walls of the housingbody 611, the double-tapered configuration of the housing passage 612acts to secure the valve component 630 within the housing passage 612.Biocompatible adhesives could additionally or alternatively be utilisedto secure the valve body 631 to the housing body 611. The housing body611 could also be further secured to the wall of the ascending aorta 23with biocompatible adhesives. Such adhesives could also be utilised inthe various other embodiments described. The catheter 2 and guide wire 1are then withdrawn from the patient, leaving the assembled heart valveprosthesis 610 in position as depicted n FIG. 29. Blood flow from theleft ventricle 17 into the ascending aorta 22 is provided for throughthe valve elements 636 whilst the same valve elements 636 prevent backflow from the ascending aorta 22 into the left ventricle 17.

It is also envisaged that the aortic valve prosthesis 600 of the sixthembodiment may be implanted using a surgical or percutaneoustrans-apical approach equivalent to the to mitral valve replacementtrans-apical approach described above in relation to FIGS. 12 through17. In such an approach, access would again be provided to the leftventricle (and ascending aorta) via a puncture in the apex of the leftventricle.

Persons skilled in the art will also appreciate various other possiblemodifications to the heart valve prosthesis and associated methods ofimplantation.

The invention claimed is:
 1. An atrioventricular heart valve prosthesisfor replacing an atrioventricular valve of a heart, said prosthesiscomprising a housing component and a valve component; wherein saidhousing component comprises: a housing body having an atrial end havinga diameter, a ventricular end having a diameter, and a housing passageextending from the atrial end to the ventricular end; said housing bodybeing configured to be located in, or adjacent to and communicatingwith, a native atrioventricular valve orifice of the heart; aventricular anchoring mechanism secured to said housing body andconfigured to engage chordae tendineae of the heart downstream of thenative atrioventricular valve orifice and within the ventricle of theheart communicating with the native atrioventricular valve orifice, saidventricular anchoring mechanism comprising a super elastic, shapememory, nickel-titanium alloy; said housing component being configurablebetween a housing collapsed state for delivery to the nativeatrioventricular valve orifice via catheterization and a housingexpanded state to engage said ventricular anchoring mechanism with thechordae tendineae of the heart to fix said housing body in relation tothe native atrioventricular valve orifice; an atrial anchoring mechanismsecured to said housing body and configured to extend over tissuesurrounding the native atrioventricular valve orifice within the atriumof the heart communicating with the native atrioventricular valveorifice and to prevent said housing component from migrating into theventricle when said housing component is in the housing expanded state,said atrial anchoring mechanism comprising a shape memory,nickel-titanium alloy; and an annular sealing member extending radiallyoutwardly from said housing body at a location between the atrial endand the ventricular end of said housing body and configured to inhibitblood flow from the ventricle to the atrium when said housing componentis in the housing expanded state with said housing body disposed withinthe native atrioventricular valve orifice, the sealing member having anouter diameter greater than the diameters of the atrial end and theventricular end of said housing body; further wherein said valvecomponent comprises: a valve body having a valve passage extendingtherethrough; said valve body being separate from said housing componentand being configured to be located at least partially within saidhousing passage with said valve passage extending along said housingpassage; and one or more flexible valve elements secured to said valvebody and extending across said valve passage for blocking blood flow ina first direction through said valve passage whilst allowing blood flowin an opposing second direction through said valve passage; said valvecomponent being configurable between a valve collapsed state fordelivery to said housing passage via catheterization following deliveryof said housing component to the native atrioventricular valve orificeand with said housing body in said housing expanded state, and a valveexpanded state to engage said housing component and/or structure of theheart to fix said valve body at least partially within said housingpassage.
 2. The prosthesis of claim 1 wherein said ventricular anchoringmechanism includes a plurality of ventricular prongs secured to andspaced about said housing body.
 3. The prosthesis of claim 2 whereinsaid ventricular prongs are each secured to said housing body by one ormore legs extending from the ventricular end of said housing body. 4.The prosthesis of claim 1 wherein said atrial anchoring mechanism isfurther configured to engage a wall of the atrium of the heartcommunicating with the native valve orifice.
 5. The prosthesis of claim4 wherein said atrial anchoring mechanism further comprises a pluralityof atrial prongs secured to and spaced about said housing body, saidatrial prongs being located such that, in use, said atrial prongs engagethe wall of the atrium.
 6. The prosthesis of claim 1 wherein saidhousing body comprises a housing body frame formed of one or moreelongate elastic housing body frame elements.
 7. The prosthesis of claim6 wherein said housing body further comprises a flexible housing wallfixed to said housing body frame and extending about said housingpassage.
 8. The prosthesis of claim 1 wherein said housing body issubstantially cylindrical.
 9. The prosthesis of claim 1 wherein saidhousing body is tapered.
 10. The prosthesis of claim 1 wherein saidhousing passage is double- tapered, defining a housing passage neckportion located between opposing ends of said housing passage, furtherwherein said valve body is double-tapered, defining a valve body neckportion adapted to co-operate with said housing passage neck portion tosecure said valve body within said housing passage.
 11. The prosthesisof claim 1 wherein said valve body comprises a valve body frame formedof one or more elongate elastic valve body frame elements.
 12. Theprosthesis of claim 1 wherein said valve component comprises a stentvalve, said valve body being configured to be fixed at least partiallywithin said housing passage by expansion of said valve body.
 13. Theprosthesis of claim 1 wherein said housing component further comprisesone or more flexible temporary valve elements secured to said housingbody and extending across said housing passage for inhibiting blood flowin said first direction through said housing passage whilst allowingblood flow in said second direction through said housing passage priorto delivery of said valve component.
 14. The prosthesis of claim 1wherein said valve component includes a collapsible anchor device foranchoring said valve body to a septum of the heart and a flexible anchorline extending between said valve body and said anchor device, saidanchor device being collapsible for delivery via catheterization withsaid valve body.
 15. The prosthesis of claim 1 wherein said prosthesisis a mitral valve prosthesis for replacing a mitral valve.
 16. Theprosthesis of claim 1 wherein said valve passage extends from a valveinlet to a valve outlet and the one or more flexible valve elements areconfigured to block blood flow in the first direction through said valvepassage from the valve outlet toward the valve inlet and allow bloodflow in the opposing second direction through said valve passage fromthe valve inlet through the valve outlet and toward said ventricularanchoring mechanism.
 17. The prosthesis of claim 1 wherein said housingcollapsed state is an unstable state and said housing expanded state isa stable state, said housing component being elastically collapsiblefrom the stable housing expanded state into the unstable housingcollapsed state and self-expandable back to the stable housing expandedstate.
 18. The prosthesis of claim 1 wherein said valve collapsed stateis an unstable state and said valve expanded state is a stable state,said valve component being elastically collapsible from the stable valveexpanded state into the unstable valve collapsed state andself-expandable back to the stable valve expanded state.
 19. Anatrioventricular heart valve prosthesis for replacing anatrioventricular valve of a heart between an atrium and a ventricle ofthe heart, said prosthesis comprising a housing component and a valvecomponent; wherein said housing component comprises: a housing bodyhaving an atrial end, a ventricular end, and a housing passage extendingfrom the atrial end to the ventricular end; said housing body beingconfigured to be located in, or adjacent to and communicating with, anative atrioventricular valve orifice of said atrioventricular valve ofthe heart; an anchoring mechanism secured to said housing body andconfigured to engage tissue of the heart; said housing component beingconfigurable between a housing collapsed state for delivery to thenative atrioventricular valve orifice via catheterization and a housingexpanded state to engage said anchoring mechanism with the sub-valvulartissue of the heart to fix said housing body in relation to the nativeatrioventricular valve orifice; and an annular sealing member extendingradially outwardly from said housing body at a location between theatrial end and the ventricular end of said housing body and configuredto inhibit blood flow from the ventricle to the atrium when said housingcomponent is in the housing expanded state with said housing bodydisposed within the native atrioventricular valve orifice, the sealingmember extending beyond the atrial end and the ventricular end of saidhousing body in a radial direction; further wherein said valve componentcomprises: a valve body having a valve passage extending therethrough;said valve body being separate from said housing and being configured tobe located at least partially within said housing passage with saidvalve passage extending along said housing passage; and one or moreflexible valve elements secured to said valve body and extending acrosssaid valve passage for blocking blood flow in a first direction throughsaid valve passage whilst allowing blood flow in an opposing seconddirection through said valve passage; said valve component beingconfigurable between a valve collapsed state for delivery to saidhousing passage via catheterization following delivery of said housingcomponent to the native atrioventricular valve orifice and with saidhousing body in said housing expanded state, and a valve expanded stateto engage said housing component and/or structure of the heart to fixsaid valve body at least partially within said housing passage; furtherwherein said housing component further comprises one or more flexibletemporary valve elements secured to said housing body and extendingacross said housing passage for inhibiting blood flow in said firstdirection through said housing passage whilst allowing blood flow insaid second direction through said housing passage prior to delivery ofsaid valve component.
 20. The prosthesis of claim 19 wherein said valvepassage extends from a valve inlet to a valve outlet and the one or moreflexible valve elements are configured to block blood flow in the firstdirection through said valve passage from the valve outlet toward thevalve inlet and allow blood flow in the opposing second directionthrough said valve passage from the valve inlet through the valve outletand toward said anchoring mechanism.
 21. The prosthesis of claim 19wherein said housing collapsed state is an unstable state and saidhousing expanded state is a stable state, said housing component beingelastically collapsible from the stable housing expanded state into theunstable housing collapsed state and self-expandable back to the stablehousing expanded state.
 22. The prosthesis of claim 19 wherein saidvalve collapsed state is an unstable state and said valve expanded stateis a stable state, said valve component being elastically collapsiblefrom the stable valve expanded state into the unstable valve collapsedstate and self-expandable back to the stable valve expanded state. 23.The prosthesis of claim 19 wherein said anchoring mechanism engagestissue of the heart that is downstream of the native atrioventricularvalve orifice and within the ventricle.
 24. The prosthesis of claim 1wherein said prosthesis is a tricuspid valve prosthesis for replacing atricuspid valve.
 25. The prosthesis of claim 19 wherein said prosthesisis a mitral valve prosthesis for replacing a mitral valve.
 26. Theprosthesis of claim 19 wherein said prosthesis is a tricuspid valveprosthesis for replacing a tricuspid valve.
 27. The prosthesis of claim19 wherein said anchoring mechanism comprises a ventricular anchoringmechanism and said housing component comprises an atrial anchoringmechanism secured to said housing body and configured to extend overtissue surrounding the native atrioventricular valve orifice within theatrium and to prevent said housing component from migrating into theventricle when said housing component is in the housing expanded state.28. The prosthesis of claim 1 wherein said housing body comprises ahousing body frame and a flexible housing wall fixed to said housingbody frame and extending circumferentially about said housing passageand axially from the atrial end to the ventricular end of said housingbody.
 29. An atrioventricular heart valve prosthesis for replacing anative atrioventricular valve of a heart between an atrium and aventricle of the heart, said prosthesis comprising a housing componentand a valve component; wherein said housing component comprises: ahousing body having an atrial end, a ventricular end, and a housingpassage extending from the atrial end to the ventricular end; saidhousing body being configured to be deployed in the nativeatrioventricular valve such that the atrial end is located within theatrium and the ventricular end is located within the ventricle, saidhousing body comprising a housing body frame and a flexible housing wallfixed to said housing body frame and extending about said housingpassage; and a ventricular anchoring mechanism secured to said housingbody and configured to engage sub-valvular tissue of the heart withinthe ventricle; an atrial anchoring mechanism secured to said housingbody and configured to extend over tissue surrounding the nativeatrioventricular valve within the atrium; said housing component beingconfigurable between a housing collapsed state for delivery to thenative atrioventricular valve via catheter and a housing expanded statein which said housing body is deployed within the nativeatrioventricular valve, the ventricular anchoring mechanism is deployedin the ventricle and engages sub-valvular tissue, and the atrialanchoring mechanism is deployed in the atrium and is positioned toprevent said housing component from migrating into the ventricle; anannular sealing member extending radially outwardly from said housingbody at a location between the atrial end and the ventricular end ofsaid housing body so as to be deployed within the atrium and inhibitblood flow between the atrium and the ventricle when said housingcomponent is in the housing expanded state, the sealing member extendingbeyond the atrial end and the ventricular end of said housing body in aradial direction; further wherein said valve component comprises: avalve body having a valve passage extending therethrough; said valvebody being separate from said housing component and being configured tobe located at least partially within said housing passage with saidvalve passage extending along said housing passage; and one or moreflexible valve elements secured to said valve body and extending acrosssaid valve passage for blocking blood flow in a first direction throughsaid valve passage whilst allowing blood flow in an opposing seconddirection through said valve passage; said valve component beingconfigurable between a valve collapsed state for delivery to saidhousing passage via catheter following delivery of said housingcomponent to the native atrioventricular valve and with said housingbody in said housing expanded state, and a valve expanded state toengage said housing component and/or structure of the heart to fix saidvalve body at least partially within said housing passage.
 30. Theprosthesis of claim 29 wherein said housing body frame, said ventricularanchoring mechanism, and said atrial anchoring mechanism are made of ashape memory alloy.
 31. The prosthesis of claim 29 wherein said valvecomponent is configured such that an atrial end of said valve bodyextends beyond the sealing member in a direction toward the atrium whensaid valve component is in the expanded state engaging said housingcomponent.
 32. The prosthesis of claim 29 wherein said flexible housingwall is made of polyester.